Using wrl data in Cycles
The material provided by your importer may need a small adjustment to display the 'vertex_colors' layer when you switch over to Cycles Render engine.
Ideally you should be able to import the .wrl while already in Cycles Render engine and let the importer set up the material correctly -- but at present this is not the case.
A solution is to add an Attribute Node to the Cycles material Node Tree and write Col into the name field. This won't display properly in texture mode, you must set the viewport shading to Rendered, or currently you will only see black.
steps

Import the .wrl as normal

Create a node material for the object,
2a. With the object selected, open a Node Editor  
2b. set the Node Tree view type to Material  
2c. Tick the box labelled Use Nodes

Add an attribute node, and write 'Col' (without quotes) into it as in the picture.

Hook up the output of the Attribute node, to the colour input of the Diffuse BSDF  node.